This applicant has filed an application for an American patent titled "An Adjustable Folding Ladder", Ser. No. 114,022, which is composed of four straight sections with three pairs of hinged joints. Each section is made up of two uprights as the legs, and connectors and rungs are set horizontally between the uprights for stepping on. Adjoining sections are connected together by two hinged joints right and left. A connector, whose both ends are separately cut with female left-winding or right-winding threads, combines with the screw of the hinged joint so that one-way turning of the connector can tighten or loosen the hinged joints for adjusting the contained angle of the two sections and for changing the height of the ladder or folding the ladder for storage.
This invention concerns another kind of a folding ladder with a different structure from the application of Ser. No. 114,022.